Configuring Certificate Enrollment for a PKI

Transcription

1 This module describes the different methods available for certificate enrollment and how to set up each method for a participating PKI peer. Certificate enrollment, which is the process of obtaining a certificate from a certification authority (CA), occurs between the end host that requests the certificate and the CA. Each peer that participates in the public key infrastructure (PKI) must enroll with a CA. Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper. Finding Feature Information, page 1 Prerequisites for PKI Certificate Enrollment, page 2 Information About Certificate Enrollment for a PKI, page 2 How to Configure Certificate Enrollment for a PKI, page 6 Configuration Examples for PKI Certificate Enrollment Requests, page 31 Additional References, page 38 Feature Information for PKI Certificate Enrollment, page 40 Finding Feature Information Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to An account on Cisco.com is not required. 1

2 Prerequisites for PKI Certificate Enrollment Prerequisites for PKI Certificate Enrollment Before configuring peers for certificate enrollment, you should have the following items: A generated Rivest, Shamir, and Adelman (RSA) key pair to enroll and a PKI in which to enroll. An authenticated CA. Familiarity with the module Cisco IOS PKI Overview: Understanding and Planning a PKI. Enable NTP on the device so that the PKI services such as auto enrollment and certificate rollover may function correctly. As of Cisco IOS Release 12.3(7)T, all commands that begin with crypto ca have been changed to begin with crypto pki. Although the router will still accept crypto ca commands, all output will be be displayed crypto pki. Information About Certificate Enrollment for a PKI What Are CAs A CA is an entity that issues digital certificates that other parties can use. It is an example of a trusted third party. CAs are characteristic of many PKI schemes. A CA manages certificate requests and issues certificates to participating network devices. These services provide centralized key management for the participating devices to validate identities and to create digital certificates. Before any PKI operations can begin, the CA generates its own public key pair and creates a self-signed CA certificate; thereafter, the CA can sign certificate requests and begin peer enrollment for the PKI. You can use the Cisco IOS certificate server or a CA provided by a third-party CA vendor. Framework for Multiple CAs A PKI can be set up in a hierarchical framework to support multiple CAs. At the top of the hierarchy is a root CA, which holds a self-signed certificate. The trust within the entire hierarchy is derived from the RSA key pair of the root CA. The subordinate CAs within the hierarchy can be enrolled with either the root CA or with another subordinate CA. Multiple tiers of CAs are configured by either the root CA or with another subordinate CA. Within a hierarchical PKI, all enrolled peers can validate the certificate of one another if the peers share a trusted root CA certificate or a common subordinate CA. When to Use Multiple CAs Multiple CAs provide users with added flexibility and reliability. For example, subordinate CAs can be placed in branch offices while the root CA is at the office headquarters. Also, different granting policies can be 2

3 Authentication of the CA implemented per CA, so you can set up one CA to automatically grant certificate requests while another CA within the hierarchy requires each certificate request to be manually granted. Scenarios in which at least a two-tier CA is recommended are as follows: Large and very active networks in which a large number of certificates are revoked and reissued. A multiple tier CA helps to control the size of the certificate revocation lists (CRLs). When online enrollment protocols are used, the root CA can be kept offline except to issue subordinate CA certificates. This scenario provides added security for the root CA. Authentication of the CA The certificate of the CA must be authenticated before the device will be issued its own certificate and before certificate enrollment can occur. Authentication of the CA typically occurs only when you initially configure PKI support at your router. To authenticate the CA, issue the crypto pki authenticate command, which authenticates the CA to your router by obtaining the self-signed certificate of the CA that contains the public key of the CA. Authentication via the fingerprint Command Cisco IOS Release 12.3(12) and later releases allow you to issue the fingerprint command t o preenter a fingerprint that can be matched against the fingerprint of a CA certificate during authentication. If a fingerprint is not preentered for a trustpoint, and if the authentication request is interactive, you must verify the fingerprint that is displayed during authentication of the CA certificate. If the authentication request is noninteractive, the certificate will be rejected without a preentered fingerprint. If the authentication request is made using the command-line interface (CLI), the request is an interactive request. If the authentication request is made using HTTP or another management tool, the request is a noninteractive request. Supported Certificate Enrollment Methods Cisco IOS software supports the following methods to obtain a certificate from a CA: Simple Certificate Enrollment Protocol (SCEP)--A Cisco-developed enrollment protocol that uses HTTP to communicate with the CA or registration authority (RA). SCEP is the most commonly used method for sending and receiving requests and certificates. To take advantage of automated certificate and key rollover functionality, you must be running a CA that supports rollover and SCEP must be used as your client enrollment method. If you are running a Cisco IOS CA, you must be running Cisco IOS Release 12.4(2)T or a later release for rollover support. PKCS12--The router imports certificates in PKCS12 format from an external server. 3

4 Supported Certificate Enrollment Methods IOS File System (IFS)--The router uses any file system that is supported by Cisco IOS software (such as TFTP, FTP, flash, and NVRAM) to send a certificate request and to receive the issued certificate. Users may enable IFS certificate enrollment when their CA does not support SCEP. Prior to Cisco IOS Release 12.3(4)T, only the TFTP file system was supported within IFS. Manual cut-and-paste--the router displays the certificate request on the console terminal, allowing the user to enter the issued certificate on the console terminal. A user may manually cut-and-paste certificate requests and certificates when there is no network connection between the router and CA. Enrollment profiles--the router sends HTTP-based enrollment requests directly to the CA server instead of to the RA-mode certificate server (CS). Enrollment profiles can be used if a CA server does not support SCEP. Self-signed certificate enrollment for a trustpoint--the secure HTTP (HTTPS) server generates a self-signed certificate that is to be used during the secure socket layer (SSL) handshake, establishing a secure connection between the HTTPS server and the client. The self-signed certificate is then saved in the router s startup configuration (NVRAM). The saved, self-signed certificate can then be used for future SSL handshakes, eliminating the user intervention that was necessary to accept the certificate every time the router reloaded. To take advantage of autoenrollment and autoreenrollment, do not use either TFTP or manual cut-and-paste enrollment as your enrollment method. Both TFTP and manual cut-and-paste enrollment methods are manual enrollment processes, requiring user input. Cisco IOS Suite-B Support for Certificate Enrollment for a PKI Suite-B requirements comprise of four user interface suites of cryptographic algorithms for use with IKE and IPSec that are described in RFC Each suite consists of an encryption algorithm, a digital signature algorithm, a key agreement algorithm, and a hash or message digest algorithm. Suite-B adds the following support for the certificate enrollment for a PKI: Elliptic Curve Digital Signature Algorithm (ECDSA) (256-bit and 384-bit curves) is used for the signature operation within X.509 certificates. PKI support for validation of for X.509 certificates using ECDSA signatures. PKI support for generating certificate requests using ECDSA signatures and for importing the issued certificates into IOS. See the Configuring Security for VPNs with IPsec feature module for more detailed information about Cisco IOS Suite-B support. 4

5 Registration Authorities Registration Authorities A Cisco IOS certificate server can be configured to run in RA mode. An RA offloads authentication and authorization responsibilities from a CA. When the RA receives a SCEP or manual enrollment request, the administrator can either reject or grant it on the basis of local policy. If the request is granted, it will be forwarded to the issuing CA, and the CA can be configured to automatically generate the certificate and return it to the RA. The client can later retrieve the granted certificate from the RA. Automatic Certificate Enrollment Automatic certificate enrollment allows the CA client to automatically request a certificate from its CA sever. This automatic router request eliminates the need for operator intervention when the enrollment request is sent to the CA server. Automatic enrollment is performed on startup for any trustpoint CA that is configured and that does not have a valid client certificate. When the certificate expires, a new certificate is automatically requested. When automatic enrollment is configured, clients automatically request client certificates. The CA server performs its own authorization checks; if these checks include a policy to automatically issue certificates, all clients will automatically receive certificates, which is not very secure. Thus, automatic certificate enrollment should be combined with additional authentication and authorization mechanisms (such as Secure Device Provisioning (SDP), leveraging existing certificates, and one-time passwords). Automated Client Certificate and Key Rollover By default, the automatic certificate enrollment function requests a new client certificate and keys from the CS before the client s current certificate expires. Certificate and key rollover allows the certificate renewal rollover request to be made before the certificate expires by retaining the current key and certificate until the new, or rollover, certificate is available. After a specified amount of time, the rollover certificate and keys will become the active certificate and keys. The expired certificate and keys are immediately deleted upon rollover and removed from the certificate chain and CRL. The setup for automatic rollover is twofold: CA clients must be automatically enrolled and the client s CAs must be automatically enrolled and have the auto-rollover command enabled. For more information on configuring your CA servers for automatic certificate rollover see the section Automatic CA Certificate and Key Rollover in the chapter Configuring and Managing a Cisco IOS Certificate Server for PKI Deployment of the Public Key Infrastructure Configuration Guide. An optional renewal percentage parameter can be used with the auto-enroll command to allow a new certificate to be requested when a specified percentage of the lifetime of the certificate has passed. For example, if the renewal percentage is configured as 90 and the certificate has a lifetime of one year, a new certificate is requested 36.5 days before the old certificate expires. In order for automatic rollover to occur, the renewal percentage must be less than 100.The specified percent value must not be less than 10. If a client certificate is issued for less than the configured validity period due to the impending expiration of the CA certificate, the rollover certificate will be issued for the balance of that period. A minimum of 10 percent of the configured validity period, with an absolute minimum of 3 minutes, is required to allow rollover enough time to function. 5

6 Certificate Enrollment Profiles Tip If CA autoenrollment is not enabled, you may manually initiate rollover on an existing client with the crypto pki enroll command if the expiration time of the current client certificate is equal to or greater than the expiration time of the corresponding CA certificate. The client will initiate the rollover process, which occurs only if the server is configured for automated rollover and has an available rollover server certificate. A key pair is also sent if configured by the auto-enroll re-generate command and keyword. It is recommended that a new key pair be issued for security reasons. Certificate Enrollment Profiles Certificate enrollment profiles allow users to specify certificate authentication, enrollment, and reenrollment parameters when prompted. The values for these parameters are referenced by two templates that make up the profile. One template contains parameters for the HTTP request that is sent to the CA server to obtain the certificate of the CA (also known as certificate authentication); the other template contains parameters for the HTTP request that is sent to the CA for certificate enrollment. Configuring two templates enables users to specify different URLs or methods for certificate authentication and enrollment; for example, authentication (getting the certificate of the CA) can be performed via TFTP (using the authentication url command) and enrollment can be performed manually (using the enrollment terminal command). Prior to Cisco IOS Release 12.3(11)T, certificate requests could be sent only in a PKCS10 format; however, an additional parameter was added to the profile, allowing users to specify the PKCS7 format for certificate renewal requests. A single enrollment profile can have up to three separate sections for each task--certificate authentication, enrollment, and reenrollment. How to Configure Certificate Enrollment for a PKI This section contains the following enrollment option procedures. If you configure enrollment or autoenrollment (the first task), you cannot configure manual certificate enrollment. Also, if you configure TFTP or manual cut-and-paste certificate enrollment, you cannot configure autoenrollment, autoreenrollment, an enrollment profile, nor can you utilize the automated CA certificate rollover capability. Configuring Certificate Enrollment or Autoenrollment Perform this task to configure certificate enrollment or autoenrollment for clients participating in your PKI. 6

7 Configuring Certificate Enrollment or Autoenrollment Before You Begin Before configuring automatic certificate enrollment requests, you should ensure that all necessary enrollment information is configured. Prerequisites for Enabling Automated Client Certificate and Key Rollover CA client support for certificate rollover is automatically enabled when using autoenrollment. For automatic CA certificate rollover to run successfully, the following prerequisites are applicable: Your network devices must support shadow PKI. Your clients must be running Cisco IOS Release 12.4(2)T or a later release. The client s CS must support automatic rollover. See the section Automatic CA Certificate and Key Rollover in the chapter Configuring and Managing a Cisco IOS Certificate Server for PKI Deployment of the Public Key Infrastructure Configuration Guide for more information on CA server automatic rollover configuration. Prerequisites for Specifying Autoenrollment Initial Key Generation Location To specify the location of the autoenrollment initial key generation, you must be running Cisco IOS Release 12.4(11)T or a later release. RSA Key Pair Restriction for Autoenrollment Trustpoints configured to generate a new key pair using the regenerate command or the regenerate keyword of the auto-enroll command must not share key pairs with other trustpoints. To give each trustpoint its own key pair, use the rsakeypair command in ca-trustpoint configuration mode. Sharing key pairs among regenerating trustpoints is not supported and will cause loss of service on some of the trustpoints because of key and certificate mismatches. Restrictions for Automated Client Certificate and Key Rollover In order for clients to run automatic CA certificate rollover successfully, the following restrictions are applicable: SCEP must be used to support rollover. Any device that enrolls with the PKI using an alternative to SCEP as the certificate management protocol or mechanism (such as enrollment profiles, manual enrollment, or TFTP enrollment) will not be able to take advantage of the rollover functionality provided by SCEP. If the configuration cannot be saved to the startup configuration after a shadow certificate is generated, rollover will not occur. > Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper. 7

8 Configuring Certificate Enrollment or Autoenrollment SUMMARY STEPS 1. enable 2. configure terminal 3. crypto pki trustpoint name 4. enrollment [mode retry period minutes retry count number] url url [pem] 5. eckeypair label 6. subject-name [x.500-name] 7. vrf vrf-name 8. ip-address {ip-address interface none} 9. serial-number [none] 10. auto-enroll [percent] [regenerate] 11. usage method1 [method2 [method3]] 12. password string 13. rsakeypair key-label key-size encryption-key-size ]] 14. fingerprint ca-fingerprint 15. on devicename : 16. exit 17. crypto pki authenticate name 18. exit 19. copy system:running-config nvram:startup-config 20. show crypto pki certificates DETAILED STEPS Step 1 Step 2 Command or Action enable Router> enable configure terminal Purpose Enables privileged EXEC mode. Enter your password if prompted. Enters global configuration mode. Step 3 Router# configure terminal crypto pki trustpoint name Router(config)# crypto pki trustpoint mytp Declares the trustpoint and a given name and enters ca-trustpoint configuration mode. 8

9 Configuring Certificate Enrollment or Autoenrollment Step 4 Command or Action enrollment [mode retry period minutes retry count number] url url [pem] Router(ca-trustpoint)# enrollment url Purpose Specifies the URL of the CA on which your router should send certificate requests. mode --Specifies RA mode if your CA system provides an RA. retry period minutes --Specifies the wait period between certificate request retries. The default is 1 minute between retries. retry count number -- Specifies the number of times a router will resend a certificate request when it does not receive a response from the previous request. (Specify from 1 to 100 retries.) url url -- URL of the file system where your router should send certificate requests. An IPv6 address can be added in the URL enclosed in brackets. For example: [2001:DB8:1:1::1]:80. For more enrollment method options, see the enrollment url (ca-trustpoint) command page. pem -- Adds privacy-enhanced mail (PEM) boundaries to the certificate request. Step 5 Step 6 Step 7 eckeypair label Router(ca-trustpoint)# eckeypair Router_1_Key subject-name [x.500-name] Router(ca-trustpoint)# subject-name cat vrf vrf-name Router(ca-trustpoint)# vrf myvrf An enrollment method other than TFTP or manual cut-and-paste must be configured to support autoenrollment. (Optional) Configures the trustpoint to use an Elliptic Curve (EC) key on which certificate requests are generated using ECDSA signatures. The label argument specifies the EC key label that is configured using the crypto key generate rsa or crypto key generate ec keysize command in global configuration mode. See the Configuring Internet Key Exchange for IPsec VPNs feature module for more information. If an ECDSA signed certificate is imported without a trustpoint configuration, then the label defaults to the FQDN value. (Optional) Specifies the requested subject name that will be used in the certificate request. x.500-name --If it is not specified, the fully qualified domain name (FQDN), which is the default subject name, will be used. (Optional) Specifies the the VRF instance in the public key infrastructure (PKI) trustpoint to be used for enrollment, certificate revocation list (CRL) retrieval, and online certificate status protocol (OCSP) status. Step 8 ip-address {ip-address interface none} Router(ca-trustpoint)# ip address (Optional) Includes the IP address of the specified interface in the certificate request. Issue the ip-address argument to specify either an IPv4 or IPv6 address. Issue the interface argument to specify an interface on the router. Issue the none keyword if no IP address should be included. 9

10 Configuring Certificate Enrollment or Autoenrollment Step 9 Command or Action serial-number [none] Router(ca-trustpoint)# serial-number Purpose If this command is enabled, you will not be prompted for an IP address during enrollment for this trustpoint. (Optional) Specifies the router serial number in the certificate request, unless the none keyword is issued. Issue the none keyword to specify that a serial number will not be included in the certificate request. Step 10 auto-enroll [percent] [regenerate] Router(ca-trustpoint)# auto-enroll regenerate (Optional) Enables autoenrollment, allowing the client to automatically request a rollover certificate from the CA. If autoenrollment is not enabled, the client must be manually re-enrolled in your PKI upon certificate expiration. By default, only t he Domain Name System (DNS) name of the router is included in the certificate. Use the percent argument to specify that a new certificate will be requested after the percentage of the lifetime of the current certificate is reached. Use the regenerate keyword to generate a new key for the certificate even if a named key already exists. If the key pair being rolled over is exportable, the new key pair will also be exportable. The following comment will appear in the trustpoint configuration to indicate whether the key pair is exportable:! RSA key pair associated with trustpoint is exportable. It is recommended that a new key pair be generated for security reasons. Step 11 Step 12 Step 13 usage method1 [method2 [method3]] Router(ca-trustpoint)# usage ssl-client password string Router(ca-trustpoint)# password string1 rsakeypair key-label key-size encryption-key-size ]] Router(ca-trustpoint)# rsakeypair key-label (Optional) Specifies the intended use for the certificate. Available options are ike, ssl-client, and ssl-server; the default is ike. (Optional) Specifies the revocation password for the certificate. If this command is enabled, you will not be prompted for a password during enrollment for this trustpoint. When SCEP is used, this password can be used to authorize the certificate request--often via a one-time password or similar mechanism. (Optional) Specifies which key pair to associate with the certificate. A key pair with the key-label argument will be generated during enrollment if it does not already exist or if the auto-enroll regenerate command was issued. Specify the key-size argument for generating the key, and specify the encryption-key-size argument to request separate encryption, signature 10

11 Configuring Certificate Enrollment or Autoenrollment Command or Action Purpose keys, and certificates. The key-size and encryption-key-size must be the same size. Length of less than 2048 is not recommended. If this command is not enabled, the FQDN key pair is used. Step 14 Step 15 Step 16 fingerprint ca-fingerprint Router(ca-trustpoint)# fingerprint 12EF53FA 355CD23E 12EF53FA 355CD23E on devicename : Router(ca-trustpoint)# on usbtoken0: exit (Optional) Specifies a fingerprint that can be matched against the fingerprint of a CA certificate during authentication. If the fingerprint is not provided and authentication of the CA certificate is interactive, the fingerprint will be displayed for verification. (Optional) Specifies that RSA keys will be created on the specified device upon autoenrollment initial key generation. Devices that may be specified include NVRAM, local disks, and Universal Serial Bus (USB) tokens. USB tokens may be used as cryptographic devices in addition to a storage device. Using a USB token as a cryptographic device allows RSA operations such as key generation, signing, and authentication to be performed on the token. Exits ca-trustpoint configuration mode and returns to global configuration mode. Step 17 Step 18 Router(ca-trustpoint)# exit crypto pki authenticate name Router(config)# crypto pki authenticate mytp exit Retrieves the CA certificate and authenticates it. Check the certificate fingerprint if prompted. This command is optional if the CA certificate is already loaded into the configuration. Exits global configuration mode. Step 19 Router(config)# exit copy system:running-config nvram:startup-config Router# copy system:running-config nvram:startup-config (Optional) Copies the running configuration to the NVRAM startup configuration. Autoenrollment will not update NVRAM if the running configuration has been modified but not written to NVRAM. 11

12 Configuring Manual Certificate Enrollment Step 20 Command or Action show crypto pki certificates Router# show crypto pki certificates Purpose (Optional) Displays information about your certificates, including any rollover certificates. Configuring Manual Certificate Enrollment Manual certificate enrollment can be set up via TFTP or the manual cut-and-paste method. Both options can be used if your CA does not support SCEP or if a network connection between the router and CA is not possible. Perform one of the following tasks to set up manual certificate enrollment: PEM-Formatted Files for Certificate Enrollment Request Using PEM-formatted files for certificate requests can be helpful for customers who are using terminal or profile-based enrollment to request certificates from their CA server. Customers using PEM-formatted files can directly use existing certificates on their routers. Restrictions for Manual Certificate Enrollment SCEP Restriction We do not recommend switching URLs if SCEP is used; that is, if the enrollment URL is do not change the enrollment URL after getting the CA certificate and before enrolling the certificate. A user can switch between TFTP and manual cut-and-paste. Key Regeneration Restriction Do not regenerate the keys manually using the crypto key generate command; key regeneration will occur when the crypto pki enrollcommand is issued if the regenerate keyword is specified. Configuring Cut-and-Paste Certificate Enrollment Perform this task to configure cut-and-paste certificate enrollment. This task helps you to configure manual certificate enrollment via the cut-and-paste method for peers participating in your PKI. 12

13 Configuring Manual Certificate Enrollment SUMMARY STEPS 1. enable 2. configure terminal 3. crypto pki trustpoint name 4. enrollment terminal pem 5. fingerprint ca-fingerprint 6. exit 7. crypto pki authenticate name 8. crypto pki enroll name 9. crypto pki import name certificate 10. exit 11. show crypto pki certificates DETAILED STEPS Step 1 Step 2 Command or Action enable Router> enable configure terminal Purpose Enables privileged EXEC mode. Enter your password if prompted. Enters global configuration mode. Step 3 Step 4 Router# configure terminal crypto pki trustpoint name Router(config)# crypto pki trustpoint mytp enrollment terminal pem Router(ca-trustpoint)# enrollment terminal Declares the trustpoint and a given name and enters ca-trustpoint configuration mode. Specifies the manual cut-and-paste certificate enrollment method. The certificate request will be displayed on the console terminal so that it may be manually copied (or cut). pem --Configures the trustpoint to generate PEM-formatted certificate requests to the console terminal. 13

14 Configuring Manual Certificate Enrollment Step 5 Command or Action fingerprint ca-fingerprint Router(ca-trustpoint)# fingerprint 12EF53FA 355CD23E 12EF53FA 355CD23E Purpose (Optional) Specifies a fingerprint that can be matched against the fingerprint of a CA certificate during authentication. If the fingerprint is not provided, it will be displayed for verification. Step 6 Step 7 exit Router(ca-trustpoint)# exit crypto pki authenticate name Exits ca-trustpoint configuration mode and returns to global configuration mode. Retrieves the CA certificate and authenticates it. Step 8 Step 9 Step 10 Router(config)# crypto pki authenticate mytp crypto pki enroll name Router(config)# crypto pki enroll mytp crypto pki import name certificate Router(config)# crypto pki import mytp certificate exit Generates certificate request and displays the request for copying and pasting into the certificate server. You are prompted for enrollment information, such as whether to include the router FQDN and IP address in the certificate request. You are also given the choice about displaying the certificate request to the console terminal. The base-64 encoded certificate with or without PEM headers as requested is displayed. Imports a certificate manually at the console terminal (pasting). The base-64 encoded certificate is accepted from the console terminal and inserted into the internal certificate database. You must enter this command twice if usage keys, a signature key, and an encryption key are used. The first time the command is entered, one of the certificates is pasted into the router. The second time the command is entered, the other certificate is pasted into the router. It does not matter which certificate is pasted first. Some CAs ignore the usage key information in the certificate request and issue general purpose usage certificates. If this applies to the certificate authority you are using, import the general purpose certificate. The router will not use one of the two key pairs generated. Exits global configuration mode. Router(config)# exit 14

15 Configuring Manual Certificate Enrollment Step 11 Command or Action show crypto pki certificates Router# show crypto pki certificates Purpose (Optional) Displays information about your certificates, the certificates of the CA, and RA certificates. Configuring TFTP Certificate Enrollment Perform this task to configure TFTP certificate enrollment. This task helps you to configure manual certificate enrollment using a TFTP server. Before You Begin You must know the correct URL to use if you are configuring certificate enrollment via TFTP. The router must be able to write a file to the TFTP server for the crypto pki enroll command. If you are using a file specification with the enrollment command, the file must contain the CA certificate either in binary format or be base-64 encoded. You must know if your CA ignores key usage information in a certificate request and issues only a general purpose usage certificate. Caution Some TFTP servers require that the file must exist on the server before it can be written. Most TFTP servers require files that can be written over. This requirement may pose a risk because any router or other device may write or overwrite the certificate request; thus, the replacement certificate request will not be used by the CA administrator, who must first check the enrollment request fingerprint before granting the certificate request. 15

16 Configuring Manual Certificate Enrollment SUMMARY STEPS 1. enable 2. configure terminal 3. crypto pki trustpoint name 4. enrollment [mode] [retry period minutes] [retry count number] url url [pem] 5. fingerprint ca-fingerprint 6. exit 7. crypto pki authenticate name 8. crypto pki enroll name 9. crypto pki import name certificate 10. exit 11. show crypto pki certificates DETAILED STEPS Step 1 Step 2 Command or Action enable Router> enable configure terminal Purpose Enables privileged EXEC mode. Enter your password if prompted. Enters global configuration mode. Step 3 Router# configure terminal crypto pki trustpoint name Router(config)# crypto pki trustpoint mytp Declares the trustpoint and a given name and enters ca-trustpoint configuration mode. Step 4 enrollment [mode] [retry period minutes] [retry count number] url url [pem] Router(ca-trustpoint)# enrollment url tftp://certserver/file_specification Specifies TFTP as the enrollment method to send the enrollment request and to retrieve the CA certificate and router certificate and any optional parameters. For TFTP enrollment, the URL must be configured as a TFTP URL, tftp://example_tftp_url. An optional file specification filename may be included in the TFTP URL. If the file specification is not included, the FQDN will be used. If the file specification is included, the router will append the extension.ca to the specified filename. 16

17 Configuring Manual Certificate Enrollment Step 5 Command or Action fingerprint ca-fingerprint Router(ca-trustpoint)# fingerprint 12EF53FA 355CD23E 12EF53FA 355CD23E Purpose (Optional) Specifies the fingerprint of the CA certificate received via an out-of-band method from the CA administrator. If the fingerprint is not provided, it will be displayed for verification. Step 6 Step 7 Step 8 Step 9 exit Router(ca-trustpoint)# exit crypto pki authenticate name Router(config)# crypto pki authenticate mytp crypto pki enroll name Router(config)# crypto pki enroll mytp crypto pki import name certificate Router(config)# crypto pki import mytp certificate Exits ca-trustpoint configuration mode and returns to global configuration mode. Retrieves the CA certificate and authenticates it from the specified TFTP server. Generates certificate request and writes the request out to the TFTP server. You are prompted for enrollment information, such as whether to include the router FQDN and IP address in the certificate request. You are queried about whether to display the certificate request to the console terminal. The filename to be written is appended with the extension.req. For usage keys, a signature key and an encryption key, two requests are generated and sent. The usage key request filenames are appended with the extensions -sign.req and -encr.req, respectively. Imports a certificate via TFTP at the console terminal, which retrieves the granted certificate. The router will attempt to retrieve the granted certificate via TFTP using the same filename used to send the request, except the extension is changed from.req to.crt. For usage key certificates, the extensions -sign.crt and -encr.crt are used. The router will parse the received files, verify the certificates, and insert the certificates into the internal certificate database on the router. Some CAs ignore the usage key information in the certificate request and issue general purpose usage certificates. If your CA ignores the usage key information in the certificate request, only import the general purpose certificate. The router will not use one of the two key pairs generated. 17

18 Configuring Manual Certificate Enrollment Step 10 Command or Action exit Purpose Exits global configuration mode. Step 11 Router(config)# exit show crypto pki certificates Router# show crypto pki certificates (Optional) Displays information about your certificates, the certificates of the CA, and RA certificates. Certifying a URL Link for Secure Communication with a Trend Micro Server Perform this task to certify a link used in URL filtering that allows secure communication with a Trend Micro Server. Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper. 18

19 Configuring Manual Certificate Enrollment SUMMARY STEPS 1. enable 2. clock set hh : mm : ss date month year 3. configure terminal 4. clock timezone zone hours-offset [minutes-offset ] 5. ip http server 6. hostname name 7. ip domain-name name 8. crypto key generate rsa general-keys modulus modulus-size 9. crypto pki trustpoint name 10. enrollment terminal 11. crypto ca authenticate name 12. Copy the following block of text containing the base 64 encoded CA certificate and paste it at the prompt. 13. Enter yes to accept this certificate. 14. serial-number 15. revocation-check none 16. end 17. trm register DETAILED STEPS Command or Action Purpose Step 1 enable Enables privileged EXEC mode. Enter your password if prompted. Router> enable Step 2 clock set hh : mm : ss month year date Sets the clock on the router. Step 3 Router# clock set 23:22:00 22 Dec 2009 configure terminal Enters global configuration mode. Step 4 Router# configure terminal clock timezone zone hours-offset [minutes-offset ] Sets the time zone. The zone argument is the name of the time zone (typically a standard acronym). The hours-offset argument is the number of hours the time 19

20 Configuring Manual Certificate Enrollment Step 5 Command or Action Router(config)# clock timezone PST -08 ip http server Purpose zone is different from Universal Time Coordinated (UTC). The minutes-offset argument is the number of minutes the time zone is different from UTC. The minutes-offsetargument of the clock timezone command is available for those cases where a local time zone is a percentage of an hour different from UTC or Greenwich Mean Time (GMT). For example, the time zone for some sections of Atlantic Canada (AST) is UTC-3.5. In this case, the necessary command would be clock timezone AST Enables the HTTP server. Step 6 Router(config)# ip http server hostname name Configures the hostname of the router. Step 7 Router(config)# hostname hostname1 ip domain-name name Defines the domain name for the router. Step 8 Step 9 Router(config)# ip domain-name example.com crypto key generate rsa general-keys modulus modulus-size Router(config)# crypto key generate rsa general-keys modulus general crypto pki trustpoint name Router(config)# crypto pki trustpoint mytp Generates the crypto keys. The general-keys keyword specifies that a general purpose key pair is generated, which is the default. The modulus keyword and modulus-size argument specify the IP size of the key modulus. By default, the modulus of a CA key is 1024 bits. When generating RSA keys, you will be prompted to enter a modulus length. A longer modulus could offer stronger security but takes longer to generate and to use. A length of less than 2048 is not recommended. The name for the general keys that are generated are based on the domain name that is configured in Step 7. For example, the keys will be called example.com. Declares the CA that your router should use and enters ca-trustpoint configuration mode. Effective with Cisco IOS Release 12.3(8)T, the crypto pki trustpoint command replaced the crypto ca trustpoint command. Step 10 enrollment terminal Specifies the manual cut-and-paste certificate enrollment method. 20

21 Configuring Manual Certificate Enrollment Command or Action Purpose The certificate request will be displayed on the console terminal so that you may manually copy (or cut). Step 11 Router(ca-trustpoint)# enrollment terminal crypto ca authenticate name Router(ca-trustpoint)# crypto ca authenticate mytp Takes the name of the CA as the argument and authenticates it. The following command output displays: Enter the base 64 encoded CA certificate. End with a blank line or the word "quit" on a line by itself. 21

22 Configuring Manual Certificate Enrollment Step 12 Command or Action Copy the following block of text containing the base 64 encoded CA certificate and paste it at the prompt. Purpose MIIDIDCCAomgAwIBAgIENd70zzANBgkqhkiG9w0BAQUFADBOMQswCQYDVQQGEwJV UzEQMA4GA1UEChMHRXF1aWZheDEtMCsGA1UECxMkRXF1aWZheCBTZWN1cmUgQ2Vy dglmawnhdgugqxv0ag9yaxr5mb4xdtk4mdgymje2nde1mvoxdte4mdgymje2nde1 MVowTjELMAkGA1UEBhMCVVMxEDAOBgNVBAoTB0VxdWlmYXgxLTArBgNVBAsTJEVx dwlmyxggu2vjdxjlienlcnrpzmljyxrlief1dghvcml0etcbnzanbgkqhkig9w0b AQEFAAOBjQAwgYkCgYEAwV2xWGcIYu6gmi0fCG2RFGiYCh7+2gRvE4RiIcPRfM6f BeC4AfBONOziipUEZKzxa1NfBbPLZ4C/QgKO/t0BCezhABRP/PvwDN1Dulsr4R+A cjkvv5mw8q+xarfcacmcze1zmkxrhjuvk9buy0v7xdlfunljua86ioe/fp3gx7kc AwEAAaOCAQkwggEFMHAGA1UdHwRpMGcwZaBjoGGkXzBdMQswCQYDVQQGEwJVUzEQ MA4GA1UEChMHRXF1aWZheDEtMCsGA1UECxMkRXF1aWZheCBTZWN1cmUgQ2VydGlm awnhdgugqxv0ag9yaxr5mq0wcwydvqqdewrdukwxmboga1udeaqtmbgbdziwmtgw ODIyMTY0MTUxWjALBgNVHQ8EBAMCAQYwHwYDVR0jBBgwFoAUSOZo+SvSspXXR9gj IBBPM5iQn9QwHQYDVR0OBBYEFEjmaPkr0rKV10fYIyAQTzOYkJ/UMAwGA1UdEwQF MAMBAf8wGgYJKoZIhvZ9B0EABA0wCxsFVjMuMGMDAgbAMA0GCSqGSIb3DQEBBQUA A4GBAFjOKer89961zgK5F7WF0bnj4JXMJTENAKaSbn+2kmOeUJXRmm/kEd5jhW6Y 7qj/WsjTVbJmcVfewCHrPSqnI0kBBIZCe/zuf6IWUrVnZ9NA2zsmWLIodz2uFHdh 1voqZiegDfqnc1zqcPGUIWVEX/r87yloqaKHee9570+sB3c4 The following command output displays: Certificate has the following attributes: Fingerprint MD5: 67CB9DC A82 9BB2171E D11BECD4 Step 13 Enter yes to accept this certificate. Fingerprint SHA1: D23209AD 23D E40D 7F9D A % Do you accept this certificate? [yes/no]: yes The following command output displays: Trustpoint CA certificate accepted. % Certificate successfully imported 22

23 Configuring a Persistent Self-Signed Certificate for Enrollment via SSL Step 14 Command or Action serial-number Purpose Specifies the router serial number in the certificate request. Step 15 hostname1(ca-trustpoint)# serial-number revocation-check none Specifies that certificate checking is ignored. hostname1(ca-trustpoint)# revocation-check none Step 16 end Exits ca-trustpoint configuration mode and returns to privileged EXEC mode. Step 17 hostname1(ca-trustpoint)# end trm register Manually starts the Trend Micro Server registration process. hostname1# trm register Configuring a Persistent Self-Signed Certificate for Enrollment via SSL This section contains the following tasks: These tasks are optional because if you enable the HTTPS server, it generates a self-signed certificate automatically using default values. Persistent Self-Signed Certificates Overview The SSL protocol can be used to establish a secure connection between an HTTPS server and a client (web browser). During the SSL handshake, the client expects the SSL server s certificate to be verifiable using a certificate the client already possesses. If Cisco IOS software does not have a certificate that the HTTPS server can use, the server generates a self-signed certificate by calling a PKI application programming interface (API). When the client receives 23

24 Configuring a Persistent Self-Signed Certificate for Enrollment via SSL this self-signed certificate and is unable to verify it, intervention is needed. The client asks you if the certificate should be accepted and saved for future use. If you accept the certificate, the SSL handshake continues. Future SSL handshakes between the same client and the server use the same certificate. However, if the router is reloaded, the self-signed certificate is lost. The HTTPS server must then create a new self-signed certificate. This new self-signed certificate does not match the previous certificate, so you are once again asked to accept it. Requesting acceptance of the router s certificate each time that the router reloads may present an opportunity for an attacker to substitute an unauthorized certificate when you are being asked to accept the certificate. Persistent self-signed certificates overcome all these limitations by saving a certificate in the router s startup configuration. Restrictions You can configure only one trustpoint for a persistent self-signed certificate. Do not change the IP domain name or the hostname of the router after creating the self-signed certificate. Changing either name triggers the regeneration of the self-signed certificate and overrides the configured trustpoint. WebVPN ties the SSL trustpoint name to the WebVPN gateway configuration. If a new self-signed certificate is triggered, then the new trustpoint name does not match the WebVPN configuration, causing the WebVPN connections to fail. Configuring a Trustpoint and Specifying Self-Signed Certificate Parameters Security threats, as well as the cryptographic technologies to help protect against them, are constantly changing. For more information about the latest Cisco cryptographic recommendations, see the Next Generation Encryption (NGE) white paper. Perform the following task to configure a trustpoint and specify self-signed certificate parameters. SUMMARY STEPS 1. enable 2. configure terminal 3. crypto pki trustpoint name 4. enrollment selfsigned 5. subject-name [x.500-name] 6. rsakeypair key-label [key-size [encryption-key-size]] 7. crypto pki enroll name 8. end 9. show crypto pki certificates [trustpoint-name[verbose]] 10. show crypto pki trustpoints [status label [status]] 24

25 Configuring a Persistent Self-Signed Certificate for Enrollment via SSL DETAILED STEPS Step 1 Step 2 Command or Action enable Router> enable configure terminal Purpose Enables privileged EXEC mode. Enter your password if prompted. Enters global configuration mode. Step 3 Step 4 Router# configure terminal crypto pki trustpoint name Router(config)# crypto pki trustpoint local enrollment selfsigned Declares the CA that your router should use and enters ca-trustpoint configuration mode. Effective with Cisco IOS Release 12.3(8)T, the crypto pki trustpoint command replaced the crypto ca trustpoint command. Specifies self-signed enrollment. Step 5 Step 6 Router(ca-trustpoint)# enrollment selfsigned subject-name [x.500-name] Router(ca-trustpoint)# subject-name rsakeypair key-label [key-size [encryption-key-size]] Router(ca-trustpoint)# rsakeypair examplekey 2048 (Optional) Specifies the requested subject name to be used in the certificate request. If no value for the x-500-name argument is specified, the FQDN, which is the default subject name, is used. (Optional) Specifies which key pair to associate with the certificate. The value for the key-label argument will be generated during enrollment if it does not already exist or if the auto-enroll regenerate command was issued. Specify a value for the key-size argument for generating the key, and specify a value for the encryption-key-size argument to request separate encryption, signature keys, and certificates. The key-size and encryption-key-size must be the same size. Length of less than 2048 is no recommended. If this command is not enabled, the FQDN key pair is used. 25

26 Configuring a Persistent Self-Signed Certificate for Enrollment via SSL Step 7 Command or Action crypto pki enroll name Purpose Tells the router to generate the persistent self-signed certificate. Step 8 Step 9 Router(ca-trustpoint)# crypto pki enroll local end Router(ca-trustpoint)# end show crypto pki certificates [trustpoint-name[verbose]] (Optional) Exits ca-trustpoint configuration mode. Enter this command a second time to exit global configuration mode. Displays information about your certificate, the certification authority certificate, and any registration authority certificates. Step 10 Router# show crypto pki certificates local verbose show crypto pki trustpoints [status label [status]] Displays the trustpoints that are configured in the router. Router# show crypto pki trustpoints status Enabling the HTTPS Server Perform the following task to enable the HTTPS server. Before You Begin To specify parameters, you must create a trustpoint and configure it. To use default values, delete any existing self-signed trustpoints. Deleting all self-signed trustpoints causes the HTTPS server to generate a persistent self-signed certificate using default values as soon as the server is enabled. SUMMARY STEPS 1. enable 2. configure terminal 3. ip http secure-server 4. end 5. copy system:running-config nvram: startup-config 26

27 Configuring a Certificate Enrollment Profile for Enrollment or Reenrollment DETAILED STEPS Step 1 Step 2 Command or Action enable Router> enable configure terminal Purpose Enables privileged EXEC mode. Enter your password if prompted. Enters global configuration mode. Step 3 Step 4 Router# configure terminal ip http secure-server Router(config)# ip http secure-server end Enables the HTTPS web server. A key pair (modulus 1024) and a self-signed certificate are automatically generated. Exits global configuration mode. Step 5 Router(config)# end copy system:running-config nvram: startup-config Router# copy system:running-config nvram: startup-config Saves the self-signed certificate and the HTTPS server in enabled mode. Configuring a Certificate Enrollment Profile for Enrollment or Reenrollment Perform this task to configure a certificate enrollment profile for enrollment or reenrollment. This task helps you to configure an enrollment profile for certificate enrollment or reenrollment of a router with a Cisco IOS CA that is already enrolled with a third-party vendor CA. Enable a router that is enrolled with a third-party vendor CA to use its existing certificate to enroll with the Cisco IOS certificate server so the enrollment request is automatically granted. To enable this functionality, you must issue the enrollment credential command. Also, you cannot configure manual certificate enrollment. Before You Begin Perform the following tasks at the client router before configuring a certificate enrollment profile for the client router that is already enrolled with a third-party vendor CA so that the router can reenroll with a Cisco IOS certificate server: 27